Add always-on-top property to app windows

ui/views/widget/widget.h

Index: ui/views/widget/widget.h
diff --git a/ui/views/widget/widget.h b/ui/views/widget/widget.h
index 151d2f3028d0100b7946586ad398d04868bf9841..3ff89e45c26b1dafa69616be183ee0b39895b058 100644
--- a/ui/views/widget/widget.h
+++ b/ui/views/widget/widget.h
@@ -461,6 +461,10 @@ class VIEWS_EXPORT Widget : public internal::NativeWidgetDelegate,
   // Sets the widget to be on top of all other widgets in the windowing system.
   void SetAlwaysOnTop(bool on_top);
 
+  // Returns whether the widget has been set to be on top of most other widgets
+  // in the windowing system.
+  bool IsAlwaysOnTop() const;
+
   // Maximizes/minimizes/restores the window.
   void Maximize();
   void Minimize();